The invention is related to a floating-caliper disc brake, in particular for automotive vehicles, with brake shoes which are positioned on either side of a brake disc and with a brake caliper which straddles the brake shoes and the edge of said brake disc. The brake caliper is axially slidingly supported on a brake carrier and has a portion on one side of the brake disc mounting a brake piston adjacent one of the brake shoes.
A floating-caliper disc brake of the kind indicated floating-caliper disc brakes of this kind, the brake shoe adjacent the brake piston is axially slid by the latter and urged against the brake disc upon actuation of the brake. The brake shoe positioned on the other side of the brake disc is moved toward the brake disc and urged against the latter by the opposite movement of the brake caliper in reaction to the movement of the brake piston, a portion of the brake caliper extending behind the other brake shoe to engage the same. At the end of the braking operation, the brake piston is retracted into the cylinder bore in the brake caliper due to the restoring effect of a piston sealing ring.
The brake shoe adjacent the brake piston is fixed to the brake piston by a claw-type spring engaging the bore of the brake piston, so that a brake clearance is established at this brake shoe. The clearance of brake shoe actuated by the brake caliper is generated by thrusts exerted by the brake disc by which the brake shoe together with the brake caliper is brought back into the brake release position countering the resistance to movement of its bearing.
A connection of the brake piston with the adjacent brake shoe requires, however, a particular configuration of the support of the brake shoe which is not always expedient. In order to render possible the clearance of the brake shoes of the disc brake without any connection between the brake piston and the brake shoe, it is, furthermore, prior art to position a holding-down spring at the brake caliper which acts upon the radially external edges of the carrier plates of the brake shoes by means of spring arms being inclined radially inwardly and in the direction of the center of the brake disc. As a result, a force component becomes effective at the brake shoes in the direction of brake release which restores the brake shoes after retraction of the brake piston.
The state-of-the-art spring arrangement has, however, the disadvantage that the restoring effect depends on the differing frictional conditions at the point of contact between spring arm and carrier plate and that the spring force and, thus, the restoring force increases as the wear of the brake linings proceeds.
It is the object of the invention to improve such a floating-caliper disc brake in such a manner that upon the release of the brake, the return of the brake shoes takes place independently of frictional forces and of the condition of wear.